Floor heating becomes more and more popular in domestic heating. Normally, such a system comprises a pipe which circulates water in a loop between a receiving portion in which the water is enriched with thermal energy and a delivering portion in which the thermal energy is delivered firstly to a floor and secondly to the ambient space. The receiving portion normally connects to, or forms part of a traditional heating system, e.g. an oil or gas fired central heating boiler while the delivering portion is normally embedded in a concrete floor construction or in similar heavy floor constructions with a large thermal capacity which thereby effects large time constants of the heating system.
There are several ways to control the thermal convection of existing floor heating systems. Traditionally, the circulated water flows with a fixed speed and a fixed supply temperature. A valve is inserted in the loop to control the amount of water which is passed through the floor. In a more advanced system, the floor comprises a loop which is isolated from the remaining heating system, and which is capable of controlling the temperature of the water which enters the floor. In other systems, the pipe is divided into separate segments with valves enabling control of the flow of water through the segments individually. The control action is typically initiated based on an observed temperature difference between an actual temperature and a desired temperature of an ambient space.
Due to the large thermal inertia, it takes relatively long time before system settings have an effect on the temperature of the floor and even longer time before the settings have an effect on the temperature of the ambient space—i.e. the room temperature. The systems are therefore difficult to control. As a consequence, an environment which is exposed to varying climatic conditions typically experience varying temperatures. As a consequence, the system causes too high heating costs and unsatisfactory climatic conditions.
Floor heating is increasingly applied in floors made from materials which are sensitive towards large temperature variations and high temperatures, e.g. wood. The control must therefore be carried out with increased precaution, and many existing systems are therefore operated with a relatively low water temperature, e.g. in the range of 30 degrees Celsius. This, however, leads to further increased time constants, and often makes it impossible to counteract sudden climatic changes. Similar problems exist in other heating and cooling systems with relatively large time constants, e.g. in connection with heating of swimming pools or cooling of ice rinks.